Mayweather didn't reveal a date, an opponent or a venue for his return bout. If Mayweather goes through with the fight, then a clash with Pacquiao wouldn't happen until 2019.

On Saturday, Mayweather released a video of he and Pacquiao together in Tokyo to announce they would square off in December. Mayweather beat Pacquiao by unanimous decision in their highly anticipated showdown in May 2015, a fight that shattered every financial record including a record-breaking 4.6 million pay-per-view buys.

The 41-year-old Mayweather (50-0, 27 KOs) said he was retired for good after knocking out MMA superstar Conor McGregor in the 10th round in August 2017.

Pacquiao (60-7-2, 39 KOs) returned from a one-year layoff in July and scored a seventh-round knockout of Lucas Matthysse to win the WBA (regular) welterweight title. Boxing's only eight-division world champion is in financial trouble and owes the IRS tens of millions of dollars in unpaid taxes even though he made about $150 million in the first Mayweather fight. He wants to get Mayweather back in the ring badly to erase what happened a little over three years ago.

"We cannot say when or exactly what date," Pacquiao told Filipino media outlet ABS-CBN News on Monday. "[Mayweather is] announcing his comeback from retirement. He wants to fight and challenge me; he wants to get my belt. Right now, we're negotiating and hoping to finalize that. I'm always available. I'm always available for him. It's important to [have the rematch], as we have unfinished business. We've been waiting for a long time."

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